Fly Ash Nanoparticle-Stabilized CO2-in-Water Foams for Gas Mobility Control Applications

Abstract

The goal of this work is to develop a novel way of beneficially utilizing two main waste products from coal power-generation plants -carbon dioxide and fly ash -by generating fly ash nanoparticle-stabilized CO 2 foam for CO 2 EOR mobility control. First, as the grain size of fly ash is generally too large for injection into reservoirs, it was reduced to nano-size by the ball-milling process. Second, dispersion stability analysis was performed to evaluate a suitable dispersing agent for fly ash nanoparticles (FA-NP). A range of surfactants (anionic, cationic, and non-ionic) was used in dilute concentrations. Surfactants were screened based on particle-hydrodynamic diameters and polydispersity index of the dispersion as measured by dynamic light scattering. Third, foam flow experiments were performed using combinations of FA-NP and various surfactants. Aqueous foam was created in-situ by coinjecting the FA-NP and/or surfactants with liquid CO 2 through a sandpack at a fixed foam quality. Foam texture, as seen in the view-cell, was used to screen suitable surfactants that stabilized strong foams. Finally, the foam flow experiments were conducted in a Berea sandstone core. Pressure drop across the core was measured to estimate the achieved foam resistance factor and the apparent viscosity of the generated foam. Nanomilling and thermal treatment processes were able to yield thermally-treated fly ash (TTFA) nanoparticles with an average size of 180 nm. Dispersion stability analysis revealed that anionic and non-ionic surfactants are suitable in dispersing these nanoparticles. Foam texture visualization demonstrated that strong carbon dioxide-in-water foam/emulsion with fine texture can be generated using TTFA nanoparticles in porous media in conjunction with a non-ionic surfactant or an anionic surfactant in dilute concentrations. Foam flow experiments in a Berea core showed that TTFA nanoparticles even in low concentrations (0.4 wt%) can significantly improve the foam stability and foam resistance factor of an anionic surfactant (in the absence of oil). Antagonistic effects were observed in foam stability in Berea core by addition of TTFA nanoparticles to nonionic surfactants. This study has the potential of not only to minimize the surfactant usage for foam-based CO 2 EOR mobility control, but also to sequester both CO 2 and fly ash in subsurface formations.

Nanotechnology Applied to Thermal Enhanced Oil Recovery Processes: A Review

“…Recent studies show that NPs are able to improve the foam stability at severe reservoir conditions and subsequently oil recovery is improved. Inorganic oxide nanoparticles such as silica [176][177][178][179][180][181][182], Al 2 O 3 [183][184][185], carbonate [186], TiO 2 [182], CuO [182], and fly ash nanoparticles [187,188] have been evaluated in foam stabilization. In particular, Figure 20a shows the oil recovery through waterflooding before (Step 1) and after (Step 2) the injection of surfactant (PSCI) in the absence (PSC1) and presence (PSC1 + SiO 2 ) of SiO 2 nanoparticles [177].…”

Silica, Fly Ash and Magnetite Nanoparticles for Improved Oil and Gas Production

“…Foam Texture Analysis: Foam texture analysis is performed as a more rigorous screening method to evaluate potential surfactants that could be used in combination with TTFA nanoparticles in stabilizing foam as it is generated in a sandpack or beadpack. Singh et al(2015) carried out these experiments at room temperature with a backpressure of 1300 psi, thus CO 2 being in a liquid state. Mixtures of 0.5 wt% of TTFA nanoparticle and 0.2 wt% surfactant solution were co-injected with carbon dioxide at a quality of 90% at a total flow rate of 2 cc/min.…”

“…Based on the above foam stability study for formulation optimization, Singh et al(2015) conducted foam flow experiments to investigate the synergy between the surfactant (non-ionic or anionic) and TTFA nanoparticles in stabilizing foam. The coreflood set-up is similar to that used for Fig.…”

Profile Control Using Fly Ash Three-Phase Foam Assisted by Microspheres with an Adhesive Coating

“…Guo et al [36,37] showed that combining fly ash nanoparticles with a surfactant mixture of alpha-olefin sulfonate and lauramidopropyl betaine results in excellent foamability and stability and highly enhanced oil recovery in microfluidics. Singh et al [38] generated nanoash-stabilized CO 2 foam for CO 2 mobility control in sandstone cores and sand packs. Their results suggested that the nanoash produced by the ball-milling method can greatly improve foam stability and the resistance factor.…”